Each class should be filed in a separate application.

Yes

The International Classification of Goods and Services (8th Edition) is followed. However, class 33 and alcoholic goods in class 32 cannot be registered in Yemen

1. Power of attorney, legalized. A general power may be used for subsequent filings. 
2. Certificate of incorporation or extract from the commercial register, with English translation, legalized. 
3. Copy of priority document, if priority is claimed, certified.

Items 1 and 2, must be submitted at the time of filing. Document 3 may be submitted within 1 month from filing date. 

90 days  

10 years from the filing date

1 year grace period 

Power of attorney, legalized; and copy of the registration certificate or last renewal certificate of the mark.

None due 

N/A

A mark becomes vulnerable to an action for cancellation if it not been used in the preceding 5 years